<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Pure CSS Retro Flip Clock</title>
    <style>
        :root {
            --digit-size: 60px;
            --digit-color: #FFEB3B;
            --background: #2C3E50;
            --shadow-color: rgba(0, 0, 0, 0.3);
        }

        body {
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
            margin: 0;
            background: linear-gradient(135deg, var(--background), #1a2634);
            font-family: 'Courier New', Courier, monospace;
            overflow: hidden;
        }

        .clock {
            display: flex;
            gap: 10px;
            padding: 30px;
            background: rgba(0, 0, 0, 0.8);
            border-radius: 15px;
            box-shadow: 0 0 30px var(--shadow-color);
            position: relative;
        }

        .clock::before {
            content: '';
            position: absolute;
            top: -10px;
            left: -10px;
            right: -10px;
            bottom: -10px;
            background: linear-gradient(45deg, transparent, rgba(255, 255, 255, 0.1));
            border-radius: 20px;
            z-index: -1;
        }

        .digit-group {
            display: flex;
            flex-direction: column;
            align-items: center;
        }

        .digit {
            width: var(--digit-size);
            height: var(--digit-size);
            background: #000;
            border-radius: 8px;
            position: relative;
            display: flex;
            justify-content: center;
            align-items: center;
            font-size: calc(var(--digit-size) * 0.8);
            color: var(--digit-color);
            text-shadow: 0 0 10px rgba(255, 235, 59, 0.5);
            margin: 5px;
            overflow: hidden;
            animation: glow 2s ease-in-out infinite alternate;
        }

        .digit::before {
            content: '';
            position: absolute;
            top: 2px;
            left: 2px;
            right: 2px;
            height: 50%;
            background: linear-gradient(to bottom, 
                rgba(255, 255, 255, 0.15) 0%,
                rgba(255, 255, 255, 0.05) 100%);
            border-radius: 6px 6px 0 0;
        }

        .separator {
            display: flex;
            flex-direction: column;
            justify-content: center;
            padding: 0 5px;
            color: var(--digit-color);
            font-size: calc(var(--digit-size) * 0.4);
            animation: blink 1s steps(1) infinite;
        }

        .label {
            text-align: center;
            color: var(--digit-color);
            font-size: 0.8em;
            margin-top: 5px;
            text-transform: uppercase;
            letter-spacing: 2px;
            opacity: 0.7;
        }

        @keyframes glow {
            from {
                box-shadow: 0 0 5px rgba(255, 235, 59, 0.2),
                           inset 0 0 5px rgba(255, 235, 59, 0.1);
            }
            to {
                box-shadow: 0 0 20px rgba(255, 235, 59, 0.4),
                           inset 0 0 10px rgba(255, 235, 59, 0.2);
            }
        }

        @keyframes blink {
            50% { opacity: 0; }
        }

        /* Ambient light effect */
        .ambient-light {
            position: fixed;
            width: 100vw;
            height: 100vh;
            background: radial-gradient(circle at 50% 50%,
                rgba(255, 235, 59, 0.05),
                transparent 60%);
            pointer-events: none;
            z-index: 1;
            mix-blend-mode: screen;
        }

        /* Scan line effect */
        .scan-lines {
            position: fixed;
            top: 0;
            left: 0;
            width: 100vw;
            height: 100vh;
            background: linear-gradient(
                to bottom,
                transparent 50%,
                rgba(0, 0, 0, 0.05) 51%
            );
            background-size: 100% 4px;
            pointer-events: none;
            z-index: 2;
        }
    </style>
</head>
<body>
    <div class="ambient-light"></div>
    <div class="scan-lines"></div>
    <div class="clock">
        <div class="digit-group">
            <div class="digits">
                <div class="digit">1</div>
                <div class="digit">2</div>
            </div>
            <div class="label">Hours</div>
        </div>
        <div class="separator">:</div>
        <div class="digit-group">
            <div class="digits">
                <div class="digit">3</div>
                <div class="digit">4</div>
            </div>
            <div class="label">Minutes</div>
        </div>
        <div class="separator">:</div>
        <div class="digit-group">
            <div class="digits">
                <div class="digit">5</div>
                <div class="digit">6</div>
            </div>
            <div class="label">Seconds</div>
        </div>
    </div>
</body>
</html>